Question: The lifespans of gorillas in a particular zoo are normally distributed. The average gorilla lives $20.8$ years; the standard deviation is $3.1$ years. Use the empirical rule $(68 - 95 - 99.7\%)$ to estimate the probability of a gorilla living longer than $23.9$ years.
Solution: The probability of a particular gorilla living longer than $23.9$ years is ${16\%}$.